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Methodical aspects of application AutoCAD in building designing
One of prominent features of construction plans and models – a great number of objects containing in them. Objects of which the building consists, as a rule, are not geometrically difficult. The number of objects influences volume of a file of the drawing and demanded for processing resources.            

In building designing are usually used technical and software of an average price category, therefore the designer-user, to put it mildly, does not feel surplus of resources and possibilities. It concerns and those who uses AutoCAD.

The volume of a file of the project and some other features aloud influence speed of its processing. If working with small projects – such as a cottage or apartment, it can and to be felt at work with large decline of productivity can appear considerable. For reduction of influence of this factor some recommendations can be offered.

Let's consider features of building subjects.

Building plotting and modelling, using, basically, possibilities and the methods inherent in any direction of design activity, has some features which should be considered at a choice of a concrete set of means from the general palette scale. Building designers deal mainly with very large objects measured in tens, and even hundreds metres in each direction whereas as units of measure of distances millimetres are used. Though work in the environment of AutoCAD, as well as the majority of CAD-programs, assumes use of real scale, that is 1:1, and the scale of a conclusion of the image is appointed to firm carriers only in the course of adjustment of options of the press, nevertheless, in the course of work absolutely it will not be possible to ignore prospective scale. Besides projected geometry, drawings, as a rule, contain set of elements of registration: Inscriptions, designations of the sizes, shadings, faltering lines. All of them, being deduced on firm carriers, should be presented correctly on them. Thus, it is necessary to think in advance of size of such elements both concerning geometry containing on the drawing, and concerning the standard sheet. Along with that each of the listed elements has own way of adjustment of scale, are possible also various methods of formation of the ready drawings, assuming various ways of the account of scale of the deduced image.

Working area. Beginning the drawing, it is necessary to have near at hand and before eyes drawing area, sufficient that on it all parts of projected object have taken places. By default at start of the program or creation of the new drawing the visible area of its space is much less, than it can be necessary for the building designer. The maximum area, visual access to which can be quickly provided by screen operations AutoCAD, is subject to adjustment by the user and is called as drawing limits. Appointed limits should surpass some total overall dimensions of projected object – that in the maximum visible area of the drawing there was a place for mentioned before registration means.

The great number of objects in drawings. At designing of building objects the simple geometry for each separately taken building element, as a rule, is used, however in any most simple drawing or in model of such elements contains much.

On the one hand, simplicity of geometry relieves of necessity to describe difficult forms. With another – the high saturation of drawings compels to care about economic from the point of view of expenses of system resources decisions. It here is understood as a correct choice of types of primitive things on which basis the logic object, and an optimum method of their creation is formed. Chosen primitive things should be as much as possible economic on demanded system resources and optimum edited from the point of view of a context of their application.

Repeating objects. The set of the objects containing in a construction plan or model, as a rule, can be carried only to the limited number of standard sizes in which limits objects are repeatedly repeating absolutely identical copies.

In this connection rather popular the functions become, allowing to create copies of objects and their files. Besides, some objects, being once are created, can then repeatedly be used not only in flowing, but also in the subsequent drawings. In AutoCAD there are the means, allowing to create, store such objects and to get to them convenient access for their repeated application. In connection with this requirement should give a proper attention the called groups of primitive things, internal both external blocks and external references.

identically changeable objects. Being identical, repeated objects, as a rule, also should change synchronously. At use of blocks and external references the changes brought in one object, are applied to set of all identical objects in the drawing. Such global editing is one of the major means of increase of labour productivity of the executor.

Extraction of the quantitative information. As a rule, the same objects demand the account of quantity of their occurrences in the drawing. It is necessary for definition of the expense of building products, building materials and money resources. With the same purpose it is required to define length, the area and volume of objects or areas, them formed. AutoCAD contains commands for automatic measurements of the geometrical objects, displaying results for acquaintance. For calculation of occurrences of blocks the special objects introduced in their structure named attributes are used. The text editing text or numerical information which then can be taken and processed in external programs for the purpose of formation of accounting documents is stored in attributes of blocks.

Connectivity of the information in various documents. In the course of designing local changes in separate drawings are made constantly, they should be considered operatively and in necessary cases to be reflected in all other drawings of the project. In an ideal such carrying over of the information should be made automatically. It is achievable at the correct organisation of work as over each separate drawing, and is global, within the limits of all working group. Various drawing documents are formed on the basis of the general initial graphic information. As a rule, it is the basic civil engineering drawings: plans, facades, cuts. Formation of other drawings consists exclusively in a filtration of the initial graphic information and addition to it the information special, but at all in audit of base geometry. To exclude repeated duplication of a specification it is possible, having provided to them access from various drawings under external references. This method allows to use in all documents of the project the updated basic graphic data right after entering into them of changes. The same purpose is served by the rational organisation of a set of the layers, allowing if necessary to form in one file set of the various drawing documents immediately reflecting changes, carried out in any of them.

Parallel work of group of executors on the general document. Sometimes it is required to provide teamwork of several executors over one document. It can be necessary in that case, for example, if in parallel with the beginning of design works specifying natural measurements are spent. In a standard case after creation of the specified building underlying cause the turned out drawings should be corrected, mechanically duplicating a cameral part of measurements. If the building underlying cause exists as the separate drawing-source on which external references from in parallel turned out drawings of the project become, their actualisation can automatically be made and immediately in process of modification of such underlying cause. Similarly by means of references to models of separate floors of a building carried out by various executors it is possible to collect its full model and on its basis to form other projections and sections.

Formation of kinds of flat projections of 3D-models. AutoCAD supposes the various approach to formation of facades and cuts of projected buildings. They can be formed manually of flat base primitive things to similarly how it occurs at paper plotting that it is impossible to recognise as an optimum method, however sometimes it is necessary. Besides, vertical projections can be received by adjustment of corresponding kinds for volume model in specific screens of space of sheet that allows to reduce essentially amount of works and provides a dynamic associative feedback of such projections with initial model. And still automatically formed projections not always provide completely the correct image: for example, they can contain superfluous lines along joints of parts of walls. Therefore the method of automatic reception on the basis of model of flat edited images of its projections which then can be finished by usual means AutoCAD is quite often applied. It is especially defensible, when the projected building should have a difficult decor which is inexpedient to reproduce in volume model, but it is necessary to reflect in drawings. In other cases, on the contrary, even if the problem of creation of volume model is not put, it can technologically appear is easier to create it in all details for formation of facades or their parts, rather than to try to catch visual reduction of a decor along bent in respect of walls at flat plotting.

The frequent conclusion of intermediate drawings. In the course of work on the project to deduce intermediate drawings it is necessary very often – including for delivery of tasks, the coordination with the customer and accessory manufacturers. It does actual the press of drawing documents from preliminary generated in space of sheet of breadboard models. Such adjustment demands no more time, than single preparation of the press from model space, however relieves of necessity to carry out it repeatedly. Such breadboard models in any file the set for various conditions of the press can be created. Sending of the adjusted breadboard model on the external device is made instantly and does not demand at the press of the additional control that provides economy of time which can be used for the decision of creative problems at performance of routine auxiliary operations. In some cases the useful can appear possibility of replacement of a conclusion of drawings on firm carriers formation of compact files of a special format which allow to look through their contents without start AutoCAD and to do listings. As these files do not suppose editing, you, transferring drawings to the customer in such form, will be assured that your design materials will not be used by competitors.

Efficiency of changes. Present market conditions and frequent paralleling of designing and building processes make rigid demands to terms of designing and efficiency of the account of wishes of the customer in the course of work. Additional means of increase of productivity, among which taken out in AutoCAD 2000 in additional group of menu Express appear the big help here. Some of the tools presented here allow in times, and even tens times to reduce time spent for separate operations. Steadfast attention the masked blocks, simultaneous deserve, for example, a scrap of set of planimetric objects on the chosen edge, operation of management by layers and some other.

Presentation visualisation. Presentation visualisation – extremely important part of building designing. It is carried out as at early stages for attraction of the customer, and in the end of work on the project for the purpose of its coordination. More often to such works apply special imaging programs. Nevertheless, AutoCAD contains powerful enough module for preparation of the photorealistic images, allowing flexibly to adjust the point of view and illumination, to appoint to parts of buildings visual properties of real materials, to apply the special effects simulating natural conditions of supervision, to enter buildings in the photographic background reproducing a real environment. In most cases these possibilities it appears enough for work with building objects.

Let's consider iron.

It is not necessary to save on a video card. In the course of work screen operations occupy a considerable share of time. On the other hand, 3D-possibilities of a video card, most likely, will appear little useful even at volume modelling.

The choice between frequency of the processor and volume of operative memory in most cases should be solved in favour of last. At work on architectural and constructive drawings operative memory will not seem superfluous.

Very important role is played by disk space. In the course of work a considerable part of information AutoCAD dumps on a disk in the form of time files of fast access. Especially it is actual, if some files of drawings simultaneously open or external references are used. The disk space basically does not happen much.

For office files AutoCAD, not including places for storage of drawings, it is necessary to have of 300-500 Mb on a disk of free space. At least. If you consider sufficient 150-200 Mb of free disk memory, at work with the big drawings the program can leave once you, without having said goodbye, and at the best you should resort to the utility of restoration of incorrectly closed drawing.

Surpluses of operative memory allow the program to address less often to a disk, and it is capable to accelerate work a little.

Let's consider scale the final drawing document.

Working with system units AutoCAD as with millimetres, at geometry creation it is possible not to care of scale of the final drawing document. It is difficult to present more ridiculous situation, than recalculation in mind or on the calculator of values entered into the computer. It would be possible to forget about scale safely up to a conclusion of the drawing to the press, if not one circumstance. Drawings contain not only geometry, but also registration elements. All of them and in the course of work on the drawing, and in its paper representation should be displayed correctly in an application context. It means that their size should be correctly correlated with other objects of the drawing and the sizes of the formed drawing document.

To number of the objects demanding such attention, concern:
- texts and text attributes of blocks for which the height of letters should be correctly adjusted;
- the drawing sizes containing both text elements, and graphic designations;
- shadings for which important correctly to define distance between the nearest strokes;
- faltering lines at which strokes and blanks between them should be correctly adjusted;
- symbols of points;
- multilines;
- the user designations on the basis of blocks.

For work with millimetres, no less than with other metric units of length, at adjustment of units the decimal system of representation of numbers should get out. Adjustment is made in starting dialogue at an input in the program or at creation of the new drawing in current session, or a command _UNITS. At adjustment of the drawing as Quick Setup or Advanced Setup the system of representation of values of length is established on the first step. To metric measurements there corresponds variant Decimal. The Eksponentsialnaja form of representation of numbers to which there corresponds variant Scientific, also is suitable for work with metric units, however is intended for measurement of very big or very small sizes. Such form of record is not provided by drawing norms.

Other variants correspond to various formats of representation of the British system, that is are intended for measurements in foots and inches, therefore for our conditions are unsuitable. At use of decimal system owing to its universality any size can be meant by system unit in any metric units of length which are defined for itself by the user. For correct functioning of system generally such appointment does not demand special registration, that is the user himself should remember, to that system unit is equal, and not to suppose errors at appointment of the sizes. Alternation of the price of unit in the course of work on the drawing is not supposed.

The told does not concern dimensional designations created in the drawing for which some liberties which description is not included into the given theme are possible.

Thus at geometry creation it is possible not to care of scale. Discrepancy of size of created objects of visible area of the screen is eliminated by various options of a command of management in the screen scale (increase) which action is similar to work of a zoom lens of a videocamera. It means that visual change of size of objects does not influence for their real geometrical sizes. Quickly to establish in the specific screen the necessary area adjustment of limits of the drawing helps.

The screen scale is not connected with scale of a conclusion of the drawing on the press, it serves only for maintenance of convenience of work. The question on exact scale necessarily demands the decision at image listing.

However, absolutely to ignore scale of the future drawing documents in the course of work it will not be possible: besides geometry by their preparation various symbols which should be displayed correctly in ready drawings are used. As designations are not objects of the real world, they have no fixed absolute sizes. The size of designations is accepted by users from reasons of their most evident representation in the drawing document.

The sizes of symbols or their parts are convenient for estimating on what they will be in paper representation of the drawing. In this case, if designations are located in the same space, as scene geometry (in model space) which image at printing will be scaled for the purpose of reduction, for preservation of their normal amount in the definitive drawing they should be increased in the respective image. Frequency rate of their increase should be equal to frequency rate of reduction of the image.

As a rule, it is not necessary to scale designations in case of their insert in sheet space.

The text size is defined in system units AutoCAD which in design-building practice as it has been stipulated earlier, correspond to millimetres. In the event that at creation of the text by the current style in which description there are no instructions on exact height of letters is established, it will be requested and can be changed at each reference to a command _TEXT or _DTEXT. Last used value is offered by default and can be confirmed by empty input. To change height of letters it is possible graphic instructions of distance in a graphic zone of the drawing or input of the new numerical value corresponding to distance in system units (millimetres), from the keyboard in a command line.

At a writing of the multilower case text by means of a command _MTEXT the height of letters can be defined or changed directly in the built in text editor.

From all auxiliary objects-designations only at work with the text the size should be established directly in the final size. Recognising that real height of the text for its normal perception there should not be less than 2.5 mm, at creation in model space in the drawings intended for a conclusion in scale 1:100, its height should make at least 250 mm. Accordingly, for scale 1:50 it should be height from 125 mm, and for scale 1:200 – not less than 500 mm, that is the normal final size of the text should be multiplied by a denominator of scale of the drawing.

In the event that it is necessary to create text primitive things alternately and in model space, and in sheet space (in which it is not necessary to recalculate their definitive sizes), it is expedient to adjust height of letters as style property and to use for each space the text style. In this case at creation of texts the height at the reference to a command will not be requested. More detailed description of adjustment of text styles is not included into the given theme.

Text attributes of blocks – it is similar to texts – at creation automatically perceive height on current text style, or allow to appoint to its each attribute in individually real size, depending on, whether it is defined as style property. In the latter case the corresponding field remains is inaccessible.

Other types of the designations, which correct kind depends on press scale, allow not to calculate their sizes in model space, and to set in their corresponding factors of scaling. The general feature here is that in an initial kind their correct display is provided, as a rule, at press scale 1:1. At work with construction plans for which press other scale factors are used, such designations become indiscernible. Return scaling is applied to them by input of its factor as corresponding parametres of options.

For shadings the scale is appointed in the field Scale on page Quick of dialogue window Boundary Hatch. For faltering lines the similar parametre is called as scale of types of lines. The general scale for all lines of the drawing is adjusted in dialogue window Linetype Manager in the field Global scale factor. At adjustment of correct representation of lines in space of model tag Use paper space units for scaling should be disconnected.

For designations of the drawing sizes and callouts all their parametres are adjusted in dimensional styles. It allows to create, on the one hand, set of uniform designations for various conditions, with another – it is easy to be switched between such sets of options instead of change of each parametre separately. Besides, such method gives the chance to change globally properties of set of dimensional designations by editing of style uniting them.

Parametres of parts of designations of the drawing sizes are adjusted in fields of a multipage dialogue window of adjustment of dimensional styles. The number of the parametres defining size of parts of dimensional designations, reaches eight. It is not forbidden to adjust all of them direct instructions of distances for each style separately, however, if identical designations for various conditions are necessary, it can appear tiresome. It is better to adjust parts on their final size in the paper drawing, and for reduction of designations in conformity with scale of the formed drawing document to use the parametre of their return scaling entered in the field Use overall scale of of page Fit of dialogue window New Dimension Style or Modify Dimension Style. Here it is necessary to enter the value equal to a denominator of scale of a conclusion of the drawing or the floating specific screen for which adjusted style intends. Changing only this parametre, it is possible to create families of the same styles for different scale drawings and fragments.

Working with the fragments of images formed directly in space of model by copying and the subsequent geometrical scaling of a set of primitive things by which the drawing site is formed, it is necessary to consider the important feature. At drawing of the drawing sizes the dimensional text is created automatically and contains the real measured value. At measurement of sites geometrically scaled a fragment automatically measured values will differ from the corresponding sizes of the drawing-source. The similar situation can arise, if dimensional designations on the basis of the image in floating specific screens are created in sheet space. The correction factor which should be entered in the field Scale factor on page Primary Units of a dialogue window of adjustment of dimensional style should be applied to updating of dimensional values in these cases. Here the number, the return frequency rates of geometrical scaling of a fragment or, accordingly, to the scale, the appointed image which contains the floating specific screen should be entered.

Often it is required to take care of scale of representation of primitive things-points. By default points are displayed by one pixel, and on the press – a stain with a diameter on a current thickness of a feather of an output equipment. Such points do not give in to scaling. They are badly distinguishable on the screen. Therefore well distinguishable symbols are quite often applied to points with the nonzero sizes, named styles of points. For appointment of size of symbols of points is available two possibilities. By default their size is set in percentage of visible area of the screen and depends on current screen increase. At such use of designations of points their sizes after the next screen operation can appear are too small or great for normal perception at viewing and the press. In the event that points are used as auxiliary objects for bindings and should not be printed, it is not a problem. After regeneration the sizes of symbols of points are restored.

Otherwise business is when points in the form of symbols are used for imitation of geometrical objects of a scene – for example, columns of a frame building. The size of such objects cannot depend on screen increase, they should have the absolute geometrical sizes. The second possibility is for this purpose used: the size of a symbol (the party of a square or diameter of a circle) is appointed in system units AutoCAD (in our case it is millimetres). At their such use scaling is not required. In the same case if the concrete sizes are appointed to the points used as auxiliary objects, visible in the final drawing, at appointment of their values it is necessary to adhere to the same principle, as in a case with texts. The demanded final size of a designation should be increased by a denominator of scale of the drawing. Unfortunately, in one drawing it is impossible to use simultaneously some styles of points that essentially limits area of their application.

If the drawing document is formed in space of sheet on the basis of the image in floating specific screens, possibility of automatic adjustment of scale of designations of the sizes and faltering lines in any specific screen irrespective of scale of the image presented to them so that to provide their correct representation at the press is provided.

In a case with the drawing sizes this method is recommended to use only if at creation of the new specific screen in it the image scale then its blocking is immediately made at once is established. Blocking means that at change of screen increase in the space of model accessible through such screen, the visible area of space of sheet is simultaneously scaled also. Therefore the scale, appointed to the image in such screen, always remains to constants. It guarantees same scale all dimensional designations created in one screen. If the screen is not blocked, the size of the dimensional designations created at various times, can differ. Thus the sizes created thus in one specific screen, in other can be displayed incorrectly. Therefore it is necessary or to avoid display in various screens of the same sites of the image, or to filter the image of the dimensional designations created in them, placing them on various layers and operating visibility of the last. In each specific screen the scale and the unique set of visible layers can be established. The described method is convenient that for all sizes it is enough to use one dimensional style. Feature of such style that at its adjustment in the field of Scale for Dimension Features on page Fit of a dialogue window of adjustment variant Scale dimensions to layout (paperspace) is established.

Universal scaling of types of lines is adjusted as follows. In dialogue window Linetype Manager to global scale factor value 1 is appropriated and tag Use paperspace units for scaling joins. Correct representation of faltering lines at such adjustment is guaranteed only in space of sheet and the specific screens located in it. Unlike dimensional designations scaled by a current kind, for maintenance of a correctness of representation of faltering lines it is not obligatory to block specific screens, and the lines created in any of screens, in all the others are displayed correctly. Such adjustment is global and influences representation of all faltering lines of the current drawing. In certain cases it can be necessary to correct representation of lines by appointment of small values global or their local scales.

Thus it is possible to create the drawing documents containing different scale the images on the basis of the general graphic information, – thus avoiding its duplication. At printing of the drawing document generated in space of sheet, the conclusion scale is established 1:1 as separate floating specific screens contain in its structure already same scale the image. Necessity apply scaling at a conclusion of such breadboard model of the drawing can to arise only if you want to unpack it on sheet more or a smaller format, without changing thus its composition: for example, at a conclusion of a control copy before the fair press for the purpose of economy of a paper and ink. Often thus drawings of format A1 on sheets of format A3 are deduced. In press options the size of a paper (A3) and conclusion scale (1:2) thus changes. At such reduction of a format the definitive scale of the drawing or separate specific screens can keep conformity to one of standard values: for example, the scale 1:50 will change to 1:100 or scale 1:100 – to 1:200.

Let's consider selection of primitive things.

Thus that iron plays high efficiency maintenance an important role, the technique, in particular – a correct choice of primitive things for formation of drawings and models has huge value.

Let's consider optimisation of flat plotting.

At flat plotting it is necessary to exclude from a palette of means a primitive thing-area [region], and sequences of pieces [line] and arches [arc] to replace with polylines [polyline].

Very difficult primitive thing, area does not give in comparison with other types of objects of any advantages to 2D-plotting. Moreover – it is very inconveniently edited: in relation to area many standard commands AutoCAD intended for change of the form of objects are inapplicable. For editing of areas the functions usually applied in solid-state modelling are used: boolean association [union], subtraction [subtract] and crossing [intersect]. Areas are more useful can to appear at volume modelling.

Advantages of polylines before sets of pieces and arches are obvious. First, polylines provide the big compactness of the data, than identical sets on geometry of simple primitive things that promotes reduction of the sizes of files. Secondly, the objects created by polylines are integral, chosen and edited as a unit while pieces and arches in a set simulating similar geometry remain isolated primitive things, in any way is real between itself not connected (except logic by which the designer was guided at their mutual placing).

To edit sites of constructions (logic objects) which do not get out entirely, it is heavy: it is required to choose all set of primitive things as a part of such object. For a choice of a polyline it is enough to choose only its one segment. The multisegment polyline is processed by construction function a equidistant contour [similarity, offset] entirely whereas, wishing to receive the same result, isolated simple primitive things of an edited set should be processed by the piece, and then to interface separate copies among themselves. Similarly functions a facet [chamfer], interface [fillet] can process a polyline on all its extent, and isolated primitive things should be chosen consistently and in pairs.

In relation to polylines such actions, as appointment of width, and also smoothing by substitution of a broken smooth curve are applicable.

At formation of difficult curves polylines in most cases should be preferred before a spline [spline]. The contours generated on the basis of direct and arc segments, give in to the exact description by means of the linear, angular and radial sizes. At the same time for fixing in form drawings a spline contour standard tools in AutoCAD are absent. It does not mean that fixing of such form is impossible basically, but she demands a special ingenuity and patience. Besides, does not prevent to reflect and on those who will take out it in nature.

In nature of ellipses [ellipse] it is more convenient to apply ellipse ovals-polylines to form and carrying out fixing. As well as true ellipses, such ovals are created by a command the Ellipse. The difference is defined by value of a system variable pellipse: for construction of ovals to it value 1 should be appropriated.

The same concerns classical architectural forms – all of them are based on combinations of pieces and arches which are reproduced corresponding segments of a polyline.

The polyline always can be dismembered on the elementary primitive things – arches and pieces. In turn on the basis of a set of arches and pieces it can be collected. Such convertibility of transformations is very convenient: other types of primitive things do not allow to address with them so flexibly.

The most clear way of change of the form of contours is moving of tops with the help “handles” [grips]. The polyline at such reference provides preservation of integrity of a contour which is not guaranteed at work with chains of simple primitive things.

Let's consider optimisation of volume modelling.

In volume modelling the correct choice of means is even more important. Here it is possible to choose from three basic classes of primitive things: extruded base, network [mesh] and solid-state [3d solid].

Solid-state objects are perceived only by those from base functions of editing which are not intended for form change. The form of firm bodies changes a set of the specific functions working not online. Action of such functions is reduced to three boolean to operations, and also to turn and moving of separate sides of solid-state objects on the set corners and distances. Insufficient flexibility of this set of functions is to a great extent compensated by possibility habitual base primitive things to generate sections of the future objects of shift and rotation, and also a way of shift of the difficult form. The elements of an architectural decor which are the most difficult objects of the project, as a rule, are reduced to of this kind to forms.

Tools for construction of universal network objects are more various. Unlike solid-state objects, networks are absolutely mobile: any top of such object can be moved arbitrarily without any restrictions. Last circumstance also does work on editing of networks by the extremely inconvenient. Supervision conditions allow to perceive only a flat projection of object and its environment; besides, there are no control devices over movings of a working point to a direction parallel to an axis of a sight. Possibly, in the presence of 3D-visualisation and corresponding tools of the control over spatial manipulations such freedom would provide the greatest freedom of creativity, however within the limits of accessible means interactive moving of tops of network objects does not provide predicted result. In most cases network object to remove and create anew easier, than to edit.

Nevertheless, as networks allow to set in coordinates position of any knot, such objects can be used for construction of as much as difficult surfaces on the basis of the digitized real objects-prototypes. Numbering is made 3D-digitajzerom, 3D-coordinates of points of a surface of physical object for construction on them a triangulable network are thus defined. Accuracy of reproduction of object is defined by quantity of the digitized knots, but even at their small number creation of similar models manually is unreasonably difficult if not to tell an impracticable problem. The specialised software automatically creating on a set of 3D-points a network with optimum topology are applied to such work.

The big advantage of networks – their modest requirements to system resources. At use even a small number of solid-state objects the volume of a file and time of performance of screen operations considerably increase. Time of regeneration of the files containing identical geometry, but realised in one case bodies, and in other networks, can differ in tens, and in special cases and hundreds times. The special contribution to weighting of files bring boolean operations. Certainly, the number of knots in network objects too influences volume of files of drawings and speed of their regeneration, however is not so critical.

Networks lose to firm bodies in the possibilities connected with cutting and truncation of geometry. Some customised applications allow to carry out such operations with network objects, however AutoCAD itself such means does not give. There are no also means for definition of points or contours of crossing of network surfaces among themselves and other primitive things.

Possibilities of creation of standard geometrical forms in both cases are identical, and in both cases created objects are not parametrical.

To unite flexibility of solid-state modelling with low resource use superficial modelling on the basis of networks the hybrid technology allows. As a rule, architectural models are created from set of objects, many of which are created once and remain invariable at all manipulations. It, for example, columns, decor elements, joiner's products, elements of the equipment and furniture. Such objects are more convenient be not to editing, and to replace entirely. They frequently have the most difficult geometry, and their repeated repetition at incorrectly chosen technology is capable to weight model hopelessly. There is a sense to arrive as follows. Owing to complexity of these elements for their creation solid-state modelling then the type of such object any more has no crucial importance can be demanded, and it can be transformed without damage to the further work to a network.

AutoCAD does not provide special function for transformations such, however with that end in view it is possible to apply successfully export/import functions – in this case with format use 3D Studio (*.3ds).

For export of objects to a format file *.3ds [File] follows in the menu [Export]. In caused at the reference to a command a dialogue window [Export Data] it is necessary in the revealing list file Type [Save as type] to establish a format 3D Studio (*.3ds), to adjust a way to a folder in which the exported file should be placed, to appoint to a file a unique name for the given folder and to press the button [Save].

After an exit it is required to choose object or a set of objects from a dialogue window and to confirm a choice with empty input. In deduced after this a dialogue window [3D Studio File Export Options] are adjusted the export parametres which consideration is beyond a theme. In most cases it is possible to leave offered options without change and to press button OK.

From format files 3D Studio (*.3ds) it is necessary for import of objects in the menu [Insert] to choose point 3D Studio. In a dialogue window [3D Studio File Import], identical to the window considered earlier [Export Data], it is required to pass file Import in a folder containing the necessary file, to choose it in the list and to press the button [Open]. In deduced after this a dialogue window [3D Studio File Import Options] are adjusted the import parametres which consideration is beyond a theme. In most cases it is possible to press the button [Add All], to leave offered options without change and to press button OK.

Import is made in the same coordinates which the exported object had. Therefore, if to make import to the same file from which export is made, having removed preliminary initial solid-state object, on its place the exact copy formed by [polyface mesh] will be inserted.

If such transformation is made with options by default, visual properties of materials for toning if they have been appropriated to initial object can be lost level-by-level structure of objects and appointment of screen colours, however, remain.

Controllable editing of the form of such network objects is almost impossible owing to described before the reasons. If there is a probability that form change is required, the initial solid-state geometry can be kept for the subsequent corrections on an empty seat of a current file or, better, in a separate file. From each updating of such object it is required to do the new exported copy, and it, in turn, to replace by import the deleted former.

Let's consider the third measurement of flat objects.

The base primitive things used usually for flat planimetric plotting can be applied to creation of volume building models also with success. For many of them two objective properties are defined, allowing to appoint it tridimentionality and parametrically to change their condition in this quality.

Property [Thickness] allows parametrically to extend a flat primitive thing in a direction, perpendicular planes of its construction, giving it additional measurement. “immense” the point becomes thus linear object, contours ([line], [arc], all kinds of 2D-polylines [polyline]) – surfaces, and areas ([solid], [circle], [trace], all kinds of 2D-polylines [polyline]) – prismatic or cylindrical bodies.

Other property – [elevation] – allows parametrically to change a vertical position of some objects, among which listed in the previous paragraph, and also [hatch], [ellipse], [region], [spline], [ray] and straight lines [xline], the lower case text [dtext] and the multilower case text [mtext], [block] and external references [xref].

To change height and level of primitive things it is possible a command _change c an option _Properties and the options corresponding to changeable parametre. The command is caused in a command line. Besides, the height of the chosen primitive things can change in not modal dialogue window [Properties], caused by a command _properties in a command line or button [Properties] from the panel of tools [Standard].

Thanks to that high-rise characteristics of such objects change parametrically, it is possible to supervise completely manipulations with 3D-models at work with them in a plan projection.

Serious restriction of the given method is what to extend initial flat object it is possible only on a straight line and only on normals to a construction plane, and resultants pseudo-3D-objects cannot have variable height; all their parties or development of the parties (for curves) – only a squared shape.

Despite the listed restrictions, base pseudo-3D-primitive things have well proved at work on building models. It is promoted by that for buildings are characteristic vertical position, and also constant height and width of sites of walls, horizontal position and a constancy of a thickness of sites of overlappings, squareness apertures at least in the bottom part, a constancy of a thickness of sites of overlappings, a constancy of sections of extended objects (for example, beams or rafters). Certainly, all chances are not settled by it. There are walls inclined, with variable cross-section, and also horizontal and vertical longitudinal section. Apertures can have any form, there are inclined overlappings and their differences within a premise. However the share of such non-standard objects in total amount is insignificant, if the case of restoration designing only is not considered. Having compared told, it is possible to notice that pulled pseudo-volume objects quite answer conditions of solved problems.

The expediency of their application consists in the following: they are very economic from the point of view of use of system resources that favourably distinguishes them from solid-state objects, and action over them, unlike objects-networks, are absolutely supervised. Being on ideology flat planimetric primitive things, they are easily edited by standard means of planimetric editing. The form of the bases prismatic pseudo-bodies and pseudo-surfaces can easily change simple moving of tops to construction planes, thus both bases change synchronously.

If the basic share of constructions to carry out base primitive things, and solid-state modelling to apply only in the most necessary cases, it is possible to achieve an essential prize in productivity. We will consider unexpected points.

For simplification of working files both at flat plotting, and at volume modelling as geometrical objects and symbols points can be applied. Except standard representation by stains in the size in one pixel on the screen and diameter of a feather at the press, points can appoint geometrical representation with the set sizes.

Such representations of points are called as styles. The palette for their choice is caused by [Point Style] in the menu [Format]. For use of the chosen sample as geometrical object to it the absolute size in current units of length, that is – for building objects – in millimetres should be appropriated. For this purpose in the dialogue window caused by a command [Point Style] it is necessary to establish the switch in position Installation of [Set Size in Absolute Units], and in the field [Point Size] to enter the necessary size.

The point is the most undemanding to resources a primitive thing. Using points in the big files, for example, as columns of a frame building, it is possible to receive a notable prize in comparison with use in the same cases of other primitive things.

Application of points in such quality is connected with essential restriction. At appointment of style it is appropriated to all points – both created earlier, and created later. To use simultaneously it is a little exemplary for various points it is impossible. Therefore the described method will appear inapplicable or limited applicable already in that case when in a building there are columns of the various sizes and the form. We will consider drawing or model processing in parts.

Not necessarily all parts of a building fairly to edit as a part of the general model. Difficult details, elements, sometimes the whole floors and fragments of a building are better for developing in separate files and only at a final stage to unite in the finished model. To process in use context a small element (for example, a column) it is irrational, as thus it is necessary to operate with volume of the graphic information, essentially surpassing that should be processed. Besides, the next objects will block object and to create hindrances at its choice and editing. Processing of large model in parts can provide the big gain in time at the expense of faster performance of any commands anyhow connected with regeneration of the image, and also more freedom at manipulations with edited objects.

Such separate fragments or are created at once in separate files, or withdrawn from a general view by export of the external block.

For creation of the external block [File] follows in the menu to choose point [Export]. In caused at the reference to a command a dialogue window [Export Data] it is necessary in the revealing list file Type [Save as type] to establish a format [Block (*.dwg)] to adjust a way to a folder in which the exported file should be placed to appoint to a file a unique name for the given folder and to press the button [Save]. After that on inquiry in a command line to choose a variant< To set new drawing>, offered by default for what it is enough to execute empty input. Then it is required graphic instructions on the screen or the list of coordinates to set a base point of the created external block and to choose exported primitive things. After choice end by empty input the primitive things included in a set will be removed from the current drawing and placed in the new. Again created file is the usual working file AutoCAD containing only a part moved to it of the general graphic information. It can be open the program for editing by the standard image.

Subsequently at return of the processed fragment to a general view it is recommended to use technology of external references. In this case the fragment can be processed in a separate initial file and after an insert, and the general model thus will automatically perceive last changes.

At an insert it is required to specify a position in which the base point defined in the course of export will be placed. For reduction of quantity of manipulations it is recommended at definition of a base point of the created external block, no less than in the course of its return to the parental drawing at appointment of a point of an insert, to specify zero coordinates. In this case the image at an insert will be automatically correct is combined.

Various floors by their working out in separate files should be created on the basis of the general prototype or by editing of a copy of a file of the previous floor. In this case they will be easy for combining in the general model, however at an insert to each of them the high-rise coordinate should be appointed individually and correspond to its relative mark.

For an insert of a fragment as the external reference in the menu [Insert] it is necessary to choose point [External Reference]. In a dialogue window [Select Reference File] is required to be passed in a folder containing the necessary file, to choose it in the list and to press the button [Open]. At a file choice it is possible to see its reduced image contained in a graphic field [Preview].

After end of a choice of a file-source of the reference the following dialogue window [External Reference] at once is deduced. In it it is necessary to disconnect a tag [Specify On-screen] in area an [Insertion point] and, without changing values in fields X and Y (in them zero values contain), to enter in the field Z the same area the value corresponding to a high-rise mark of a fragment. After that it is necessary to press button OK.

For fine details and separate repeatedly repeating elements of a building – such as a column, at export it is necessary to specify a base point not in the beginning of coordinates, and in a characteristic place of the object, for example, in the center of the basis or the left bottom corner. At introduction of such object in the general model the insert point should be defined direct graphic instructions. For this purpose to [Specify On-screen] in area [Insertion point] should be included.

Let's consider integration of objects of editing.

One of the reasons of decline of productivity at work with the sated drawings and difficult models is the abundance of isolated primitive things. The majority of them are parts of logic compound objects, remaining thus independent. Complexity of a choice of such objects consists that is necessary to include in a set many its separate parts. Global ways of a choice, such as simple or a framework secant, are in most cases inefficient, as at high density of the image superfluous objects for which removal of a command of a global choice are already inapplicable get to a set.

Partly the problem dares application of well thought over structure of layers. If primitive things are distributed on layers by correctly, their visibility and consequently availability to a choice is easy for operating, changing a condition of layers bearing them. Nevertheless, for application at a choice of each logic object procedure of management by a condition of layers is a little heavy. In the drawing some tens, and sometimes over hundred layers can contain, therefore management of them represents a separate problem for which decision in AutoCAD the special means which description is beyond a theme are provided. The most obvious decision of a problem of a choice of difficult logic objects is association of all primitive things making it in the compound object chosen and edited as a unit.

The elementary way of such association – creation of the called groups of primitive things. The group is object AutoCAD having a unique name and uniting primitive things entering into its structure in such a manner that at a choice of one of them all other objects of group get out, and the subsequent manipulations concern all set. To choose groups it is possible on their names, and it is absolute addressable as names cannot repeat even at absolutely identical on structure and an arrangement of primitive things. At any ways of cloning new groups with automatically appointed names in a special format are created. The separate objects united in group, keep independence and if necessary can be liberated temporarily for individual editing.

For group creation it is necessary to cause a command _group in a command line. In the menu and in a standard set of panels of tools the call of the given function is not provided. At the reference to a command the dialogue window [Object Grouping] is deduced. In the field [Group Name] it is necessary to enter a unique name then to press the button [New]. The dialogue window thus temporarily leaves from the screen, and in the released area of the drawing it is required to choose united objects. After end of a choice of primitive things by empty input the dialogue window is restored with a name of again created group, containing in the list. For procedure end it is necessary to press button OK.

The condition of existing groups changes with use of the same command. Temporarily to release or again to unite objects of group it is possible having chosen her name in the list and having pressed the button [Selectable], thus the group condition varies on the opposite. The interface for work with groups in AutoCAD LT differs by the form a little, but is functionally identical. More detailed consideration of management by groups is beyond a theme.

Simplicity of a choice of the difficult compound objects, reached by means of groups, allows to reduce the general time of their editing considerably.

More effective from the point of view of economy of resources of system is association of primitive things in blocks [block].

Blocks, as well as groups, are called objects AutoCAD, however unique names are appropriated not to each separate such object from among identical on structure and geometry, and their general prototype named definition of the block and invisibly stored in a database of the drawing. All objects created on its basis, are called as block occurrences, bear a name of the prototype and repeat its geometry. As well as groups, blocks contain one or several enclosed primitive things, and also get out and edited as a unit. Their useful properties are not settled by it.

Block definition is stored in a drawing database in the single copy, and all occurrences are only references to it. Occurrence in addition to a block name contains only the information on its position in drawing space so each new occurrence of the block increases volume of a working file slightly. Using blocks, it is possible to create in drawings more number of objects, than usual way. However, it is not reflected in use of video resources.

Other important property of blocks is inheritance by all occurrences of the changes brought in definition. Thus, necessity disappears to edit each separate object of some type for maintenance of their uniformity – enough only to connect with a name of this block the new changed geometry or by means of special procedure to edit one of its occurrences directly in a context of its use in the drawing or model; thus all objects identical to it will change synchronously. It is not forbidden to use various names for each of identical objects-blocks, however in that case it will not be possible to take advantage of the advantages of a technique connected with global synchronous editing and economy of resources of system.

Drawing is necessary for creation of new definition of the block [Draw] in the menu to choose point [Block], and in the revealed subordinated menu – point [Make]. It is possible to press also the button [Make block] panels of tools [Draw]. In caused at the reference to a command a dialogue window [Block Definition] is required to execute following actions in any order:
- by means of the button [Pick point] to leave in working area of the drawing and to specify a base point;
- by means of the button [Select objects] to leave in working area of the drawing and to choose united objects;
- to type in the field [Name] a unique name for the created block;
- to define, properly to arrive with initial primitive things, to establish the switch in one of possible positions – [Retine], [Convert to block], [Delete].

After that it is necessary to press button OK. Consideration of other options, possible in this dialogue window, is beyond a theme.

Before the certain block it is necessary for an insert in the menu [Insert] to choose point [Block]. It is possible to take advantage also of the button [Insert Block] on the panel of tools [Draw]. In caused at the reference to a command a dialogue window the block [Insert] follows in the revealing list [Name] to choose a name of the necessary block. After that it is necessary to press button OK, and after closing of a dialogue window in working area of the drawing to define an insert point with which the base point of created occurrence of the block will be combined. Consideration of other variants of options, possible in this dialogue window, is beyond a theme. Have not found here reflexion cases of an insert of external blocks, and also blocks from external files, no less than use of not modal dialogue window [DesignCenter].

In many respects similarly to blocks [external reference] which operate, however, use geometry not from a database of a current working file, and from external files. Contained contained the external reference it is pumped up in operative memory at its insert or updating, or at opening of a working file into which it has been inserted in one of the previous sessions, it is direct from a file-source accessible in local, network and even web-access. As the description of such objects is stored out of a drawing file does not affect its disk size; it, however, does not influence requirement in operative or video memories. Work with external references has been considered above.

Let's consider an exception of repetitions.

To save resources and, as consequence, to achieve more high efficiency it is possible also, avoiding duplication of the graphic information at creation of fragments and formation of various drawing documents on the general graphic basis. Often various to destination drawings use the same geometry as an underlying cause. For example, basic building plans are used as an underlying cause for drawings of engineering sections. Duplications of such plans can be avoided, addressing to them under the scheme of use of external references described above.

Similarly, using the same geometry, it is possible to form specific drawing documents in one general file. The technology of formation of breadboard models of drawing documents in space of sheet on the basis of floating specific screens [viewports] is for this purpose used. Working drawing AutoCAD can contain set of such breadboard models named [layouts]. In turn, each sheet-breadboard model can contain many specific screens, and each such screen irrespective of others – the part of the general image in any chosen scale and thus to display only contents of the necessary layers. Establishing in specific screens various scale of the image, it is possible to form drawings of fragments and details on the basis of the basic geometry. Individually adjusting in specific screens sets of visible layers, there is a possibility to display in them only the part of the general information concerning concrete specific drawing documents. Through such adjusted specific screens you get access to space of model for editing. It is possible to unite, for example, in one such working file the general basic plan, the graphic information for the plan of premises, the plan of floors, the plan of ceilings, the working plan of walls and apertures, the plan of overlappings, the plan of arrangement of the equipment, and then in specific screens of concrete breadboard models to filter this information, leaving visible only the basic plan and the necessary addition to it. At use of this method in case of the changes brought in the basic plan, repeated reduction of expenditures of labour in comparison with the traditional approach as it is necessary to execute once only the updating which results will be reflected in all specific screens of the united is reached. Owing to great volume of the options necessary for creation and management by breadboard models and floating specific screens, these actions here are not considered.


Sources:
1. Rossolovsky A. AutoCAD – features of application in building designing//CADmaster, #5 (5), 2000 [http://csf.ru/file/OleGcWspyjtktUnX8295266/cm_05_autocad.pdf]
2. Rossolovsky A. AutoCAD – features of application in building designing: scale//CADmaster, #1 (6), 2001 [http://csf.ru/file/dfcrYPOFVyPLCjqa8295267/cm_06_autocad.pdf]
3. Rossolovsky A. AutoCAD – features of application in building designing. Productivity optimisation//CADmaster, #4 (9), 2001 [http://csf.ru/file/HUigouWRbJPqOuvw8295265/cm_09_autocad_str_proekt.pdf]

The author: Челябэнергопроект
Date: 07/22/2009

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